An optical frequency-domain interference microscope with a liquid-crystal Fabry-Perot interferometer as an optical frequency-scan device was developed for microscopic three-dimensional shape measurements. The proposed system can perform absolute measurement of the discontinuous surface profile of a microscopic object without use of mechanically moving components such as a piezoelectric transducer or a grating spectrometer. Experimental results are presented that demonstrate the validity of the principle.
Spectroscopic investigations are carried out on the radiation emitted from laser-induced plasma on a NaCl crystal surface. It is found that all atomic lines emitted from plasma produced by laser irradiation in air are broadened and some of them are self-reversed, while the self-reversal is not observed for plasma induced in vacuum. Self-reversal occurs for the pressure of ambient gas above 1.3 kPa. It is found from line broadening, mainly caused by resonance and the Stark effect, that the Na atom concentration in the plasma is 5.3 x loz4 m-3. Observed time-resolved spectra agree with a model that the plasma generated by laser irradiation is composed of a hot core and a low-temperature periphery, both behaving, respectively, as emission and reabsorption centers and expanding at a speed determined by the ambient gas pressure. I) 3-5-1 Johoku, Hamamatsu 432, Japan.
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